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Aviation History
1937
1937 - 0504.PDF
IQ8 FLIGHT. FEBRUARY 25, 1937. CORRESPONDENCE The Editor does not hold himself responsible for the views expressed by correspondents. The names and addresses of the writers not necessarily for publication, must in all cases accompany letters intended for publication in these columns. LIGHTS UNDER BUSHELS? I HAD the pleasure of listening to Mr. Fedden's lecture on the Trend of Air-Cooled Aero Engines. Along with others I went specifically to hear what was thought would be a very interesting lecture and a rousing discussion. The indications for a good discussion were (i) that Mr. Fedden was asking for advice from the aircraft people and proffering some to the' engine people ; (2) that he is rather dogmatic in his state ments, and usually very pro-radial and air-cooling. Which one expected would again arouse the in-line air- and liquid- cooling camps. We heard the good lecture, but did we hear a good discussion or any helpful advice from an audience of approximately 300, representing the brains of the aircraft industry ? No, sir! Only one aircraft man had anything to offer and that was apparently known to Mr. Fedden; the rest just failed to utter a word. The in-line and rival radial camps had not a word to say, despite the slight which Mr. Fedden had given them by saying that we had nothing in this country between the Gipsy VI and his own engine sizes. The liquid-cooling people were also silent. So when Major Green made the insinuation that all the best brains in ihe country are at Filton, one was inclined to agree that this is so, or else that the other engine camps are either not capable of arguing with Mr. Fedden, or no longer have an argument against the radial engine. Or, on the contrary, must we accept the other view that it is the conservatism of the British people which prevents them giving anything away ? They do not mind copying any ideas they can get from anyone else, but they just hate to let anyone know what they are doing. It's a great pity they cannot come out into the open as do the Americans; they might just as well do so, because there is no such thing as a secret in the aircraft industry. This is the second lecture which I have attended where the lecturer has asked for information and co-operation from a learned body; the result has been the same on each occasion. So if there are anv other great minds, like Mr. Fedden and Mr. Ricardo, considering asking for advice from their con temporaries, let them be warned that they themselves are the only ones who will -do any giving. Further strength to my conclusions was lent by two foreign gentlemen who enttied.the discussion, despite the disability of a foreign tcngue, and were the only people who had any thing technical to discuss. In conclusion, I would like to thank Mr. Fedden for a fine lecture and also lor doing what so few people do now, that is, replying to the discussion verbally and without favour. I do regret though that he did not tell us a little about his very attractive sleeve valves, and compare them with the poppet valve. F. GREAVES. Hayes, Middlesex. RELATIVE RELIABILITY REFERRING to Mr. Steve Hill's letter in the issue of January 14 concerning the relative reliability of aero and motor cycle engines. I should like to add a few thoughts in support of the Editor's comment. Until recently I have been a student of the College of Aeronautical Engineering, part of whose works are situated at that haven of speed, Brooklands. I therefore had the oppor tunity of observing the preparation and performance of all things that attempted to function in accordance with the " ideal Otto cycle." First, I should like to declare that Mr. Hill has nc grounds in estimating the failure of aircraft engines as being frequent. The extraordinaiy claims of certain aero engine manufacturers and airline companies prove that the failures that do occur are few and very far between. The few there are, especially when they are in connection with some stunt flight, always receive the full attention of the daily papers. Of these failures a certain number could be traced to the ignorance and care lessness of pilots (e.g., operation of altitude controls), and not to the ground engineer who signs for the responsibility of the correct functioning of the machine. Mr. Hill may not be familiar with the duties and responsi bility of a modern licensed ground engineer (or with the know ledge he possesses as compared with a garage mechanic) or even with the precautions, inspections and red tape that'are attached to the maintenance of an airworthy aircraft; if he is he will readily realise that the engineer cannot afford to take the responsibility of a man's life casually, and every safe guard and precaution (within the human element) must neces sarily be taken. During the last two year's I have owned four road vehicles in all (each at different periods!), and in travelling from London to Newcastle, a distance of nearly 300 miles, I have always had to stop for some little thing, i.e., oil leaks, primary wire from coil breaking, radiator leaks, and so 011 On one occasion, with a brand new motor cycle costing over ^90, the throttle cable broke. The point is that these little mishaps could hardly be classed as engine failure on the road, but in the air they would be, a forced landing with a possible crash being the net result. * From a technical aspect the following cannot be over looked. First, the factor of strength for a given weight hardly enters into the design of a road vehicle (even a racing motor cycle) to the same extent as it does in the aero engine. The parts of a racing motor cycle can be given a more than desirable factor of safety without appreciably affecting the performance. It must also be remembered that a motor cycle engine is a comparatively simple unit involving the minimum number of moving parts. 1 cannot appreciate Mr. Hill's statement that the road vehicles he mentions have a harder time than the aero unit. After all, the two are each designed for a particular purpose. The aero unit has to contend with variations of temperature and pressure, bringing in ice formation in carburettors, variation of oil viscosity, variation of boiling point of coolant, mixture strength problems, air density, and so on, all of which are peculiar to its own purpose. As the Editor remarked, the aero motor runs at, maybe, o/ioths full throttle for a duration of time that will increase the risk of oil leaks and fatigue failures, and I consider it to be nearer its stress limit than any loiry that is built like a battleship! A cavity or small nick in an aero engine con-rod is sufficient to scrap it, and, oh boy, have they got to be polished! The average aero engine, correctly serviced (which they have to be), seems to last almost as long as the eternal cargo boat. We change our modern cars every two years. Why? Because they are no longer reliable. I do not know whether Mr. Hill considers that the motor cycle engine is superior because it can develop 37 b.h.p. from '499 c.c. But no fair comparison of b.h.p. per litre can be made between two different cylinder sizes, and an aero engine cylinder bore is generally between 4 and 6 inches with a consequently smaller surface-volume ratio. This affects heat loss and the highest useful compression ratio employable. If Mr. Hill reads the requirements of a type test in A.p. 1208 he will not wonder why British aero engines have achieved such a fine reputation for reliability. R. TOWERS. Rochester. I FIXING THE FIXTURES WOULD like to suggest that the various organisers of filing displays and race meetings send you now the dates on which they intend to hold their meetings, so that entrants and demonstrators know roughly when they will be able 0 race or demonstrate if invited. Last season we had cla~"Bjj> fixtures, and in certain instances some of us were forced give great displeasure by our not appearing. I fully appreciate the fixture list issued by the Royal Aen Club, but this covers only the major events, and the minor, but equally important, events are sprung on us a wee two before they are due to take place. , , The Roval Automobile Club issues, in January, a comPJ5 0 list of the trials, both major and minor, and an intenaii.B entrant knows the position for the year. London, S.W.6. P. J. FIELD-RICH^' A Reading Appointment hag COL. M. ORMONDE DARBY, of Rolls-Royce, Wc;' and been appointed to the Board of Directors of ^nlU1> ,j Powis, Ltd., in succession to the late Mr. Arthur W or» •
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